The fuel tanks of vehicles have certain electrical apparatus therein, including a detector for detecting the volume of liquid in the tank and a pump for pumping fuel from the tank to the engine of the vehicle. Wires extend from outside the tank through an opening and into the tank to connect the electrical devices inside the tank with the apparatus of the vehicle. Each of the wires typically consists of about twenty smaller strands of copper wire wound together and surrounded by a plastic insulation layer, which is gasoline resistant. The wires passing through the walls of the tank are sealed against leakage by a grommet.
It has been found that the chemicals of a hydrocarbon fuel form a vapor which migrates between tiny gaps in the strands of wire, inside the insulating coating surrounding the wire. Regulations of the United States government prohibit virtually any leakage of fuel from the fuel tank and therefore, if wires passing through the walls of a fuel tank are not adequately sealed, the vehicle will violate government regulations.
To prevent all of the forgoing, it is desirable to provide a grommet fitted into the opening of a fuel tank that permits the wires to pass therethrough, but provides a seal to prevent gasoline vapors from migrating between the strands and outside of the tank.